Method for laser writing multiple updatable miniature 2-D barcode data bases for electronic commerce

ABSTRACT

A method and system for recording and storing digital data on optical memory cards and labels in the form of miniature bar codes using laser recording of optical storage media to create multiple updatable, miniature 2-D bar codes, storing about 15 to more than 500 times as much digital data as the widely-adopted PDF-417, 2-D bar code. The optical storage media is of the DRAW (direct-read-after-write) type which requires no post processing. The optical storage media is pre-formatted with tracks to precisely locate the recorded microscopic data spots. Groups of these microscopic data spots form data bars which in turn form data pixels whose dimensions are at least four times greater linearly and 16 times greater in area than the microscopic data spots. The data pixels can be read with photodetector arrays such as CCD arrays.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.09/389,397, now U.S. Pat. No. 6,145,742 filed Sep. 3, 1999.

TECHNICAL FIELD

The present invention relates to a method of laser writing multipleupdatable 2-D bar codes on optical memory cards and labels which arereadable with a photo-detector array such as a CCD array.

BACKGROUND ART

The commercial fields for linear optical data storage include opticalmemory cards, two-dimensional bar codes, and digital sound on motionpicture films.

The PDF-417 (Portable Data File), two-dimensional bar code has become awidely accepted way of storing data on cards, documents, and packages.It is used to encode graphics, including fingerprints. It has begun tobe used as a form of postage stamp printed by a laser printer connectedto a personal computer following authorization over the Internet. ThePDF-417 specification was disclosed in 1991. PDF-417 utilizes imageswith minimum dimensions of about 150 microns. An earlier, higherresolution form of two-dimensional bar code was disclosed in U.S. Pat.No. 4,634,850 entitled, “Quad Density Optical Data Systems,” assigned toDrexler Technology Corporation, which was filed Nov. 4, 1985, and issuedJan. 6, 1987. A closely related patent is U.S. Pat. No. 4,786,792 issuedNov. 22, 1988, which is also assigned to Drexler Technology Corporation.These two patents relate to reading a high-resolution form oftwo-dimensional bar codes with image dimensions of 3 to 35 micronscompared with the 150-micron image dimension of PDF-417. Examples ofpatents directly related to the PDF-417 system are U.S. Pat. Nos.5,243,655, 5,304,786, and 5,319,181 filed from 1990 to 1992 and issued1993 and 1994, which are assigned to Symbol Technologies Inc.

Other 2-D bar code products, in addition to PDF-417, include Aztec, Code16K and Code 49. When PDF-417 is referred to in this application, it ismeant when applicable, to include other 2-D bar code products as well. Anine-page article entitled “Fundamentals of Scanning New 2-D Codes withCCD Area Imagers”, has been published by Auto Image ID, Inc. of CherryHill, N.J., 08003.

Three patents have been assigned to Drexler Technology Corporation whichinvolve the laser recording on reflective optical data storage mediumusing a microscopic laser beam of one to a few microns in diameter tocreate eye-visible images formed from pixels (picture elements), whichin turn are formed from groups of 4, 9, or 16 closely-spacedlaser-recorded microscopic spots. These pixels are used to create visualalpha-numeric characters or images, including portrait images of people.The three Drexler Technology patents are U.S. Pat. No. 4,680,459entitled, “Updatable Micrographic Pocket Data Card,” U.S. Pat. No.4,814,594 entitled, “Updatable Micrographic Pocket Data Card,” and U.S.Pat. No. 5,421,619 entitled, “Laser Imaged Identification Card.”

Methods and apparatus involving linear optical data storage of data onmotion picture film are described in the following seven U.S. patents.In these cases the digital optical data represents motion picturedigital sound. Two of those patents, assigned to Drexler Technology, areU.S. Pat. Nos. 4,503,135 and 4,603,099. Patents assigned to SonyCorporation in this field include U.S. Pat. Nos. 5,471,263, 5,523,996,5,543,868, and 5,666,185. One of the relevant motion picture soundpatents assigned to Dolby Laboratories is U.S. Pat. No. 5,710,752.

Another relevant patent is recently-issued U.S. Pat. No. 5,932,865assigned to Drexler Technology Corporation, which is entitled,“Anti-Counterfeit Validation Method for Electronic Cash Cards Employingan Optical Memory Stripe.” Two sentences in the abstract point out therelevant features of this patent; namely, “Such counterfeiting can beinhibited by bonding an optical memory stripe to the smart card withpre-recorded or post-recorded validation data on the card. This opticalvalidation data would be read with a photodetector array and could betransmitted to the recipient during funds transfer and/or used locallyto control dispensing of cash.” This patent explains the importance oflaser recording data which are readable with CCD arrays, but does notdisclose the method of the present invention.

Typical optical memory cards utilize a 35 mm or 16 mm wide, reflectiveoptical memory recording stripe which stores about one to four megabytesof data when 2.5 micron spots and 12 micron track-to-track spacings areused. The reader/writer device sells for about $2,500, and read-onlydevices for those cards are also expensive because of the precisionrequired to track the digital data on the optical card with a low powerlaser diode. Customers have requested an inexpensive, read-only devicefor the optical memory cards, and it is believed some customers wouldprobably accept a somewhat lower data-storage-capacity card if thatwould lead to an inexpensive read-only device.

It is the object of the present invention to devise a method andapparatus for laser recording of a single or multiple two-dimensionalbar code(s) readable with CCD or other photodetector arrays and withdata storage capacities ranging from about 15 to more than 500 timesgreater than that of PDF-417 bar codes. Another object is to utilizedata-pixel-based two-dimensional bar codes on cards or labels forauthentication, validation, authorization, or identification involvingInternet and Intranet E-Commerce transactions, documents,communications, and manufactured products. Another object of theinvention is to devise a method and apparatus to make CCD-readdata-pixel-based two-dimensional bar codes updatable. Another object isfor an optical memory card to be utilized in reading and writingmicroscopic data spots that can be grouped into large data pixels toform single dimension bar codes known as 1-D bar codes. The 1-D bar codeproduct types include Code 39, Code 93, Code 128, Code 11, Code B, CodaBar, EAN, UPC, MSI, PostNet, Royal Mail (RM 45CC), and Telepen.

DISCLOSURE OF THE INVENTION

The above objectives have been met by a pre-formatted, laser-recordableoptical memory stripe or patch being bonded to a plastic card, or to alabel medium coated with an adhesive. The laser recording materialshould be of the DRAW (direct-read-after-writing) type where laser datais instantly recorded without a post processing operation. Thepre-formatted data tracks on the optical memory stripe or patch would beseparated by a distance of about 5 microns to 40 microns and preferably,to accommodate existing commercial equipment such spacing should beabout 12 microns, which represents an ISO standard for optical memorycards. The 12 micron spacing would include a linear edge region 2microns wide and a linear recordable region 10 microns and thus anedge-to-edge spacing of 12 microns.

The laser-recorded microscopic data spots are defined as in the range ofbetween 0.6 microns to 3 microns in diameter but more typically foroptical memory cards at about 2.5 microns in diameter. The number ofmicroscopic data spots that could fit across a track width could be assmall as two and as many as seventy, with about two to six beingpreferred.

Whereas read-only devices utilizing laser tracking of pre-formattedtracks are expensive, a read-only device using a linear CCD array toread multiple tracks encompassing large data pixels can be inexpensiveunder the right design conditions. To minimize data errors, at least twoor three photosensitive detectors of the photodetector array should readeach data pixel. The use of 7- to 10-micron size data spots with a CCDarray would work technically but might not lead to the lowest priceread-only device today, owing to the cost of the required CCD array. CCDarrays become lower in cost when the size of the data spots being readare greater than 10 microns, but data storage capacity of an opticalmemory card is reduced for larger data spots by the square of the dataspot size. If the data pixels are used to form miniature versions ofstandard one-dimensional or two-dimensional bar codes are large enoughthey can be scanned and read with a laser beam and one or more singlephotodetector(s).

The objects of the invention are achieved by creating an array ofuniform data spot pixels, or simply data pixels, whose linear size mightbe as small as seven microns or greater than 50 microns by use ofproperly arranged groups of spots, preferably about 2.5 microns indiameter. Smaller spots can be used, but then more of them would have tobe utilized to create the large data pixels. Larger spots could be used,but laser diodes have limited output powers, and spreading the beam tolarger diameters would reduce recording efficiency. The method involvesthe recording of a series of 2.5 micron spots in sequence without thenormal 2.5 micron spacing between them so as to create a continuous databar of lower reflectivity, for example, 25 microns long and 2.5 micronswide. For commercial optical memory cards, the recorded spots arerecorded in the center of the 10-micron wide, highly reflective flattrack defined by a 2-micron wide, low reflectivity border region alongeach edge of the 10-micron wide data track. Thus the center-to-centerspacing between spots centered in adjacent tracks is 12 microns. Sincethe goal is to transform a 10 micron by 25 micron region of a track fromhigh reflectivity to low reflectivity to create a data pixel, the first2.5 micron by 25 micron bar may not necessarily be recorded in thecenter of the 10-micron track. Recording it anywhere in the track leavesroom for a second, and probably a third, 2.5 micron by 25 micron bar tobe recorded in the same track. Thus in that 25-micron long, 10-micronwide reflective track, 5 to 7.5 microns of width are taken up by the lowreflectivity laser-recorded data bars. The remaining unrecorded trackwould remain at a high reflectivity, perhaps in the range of 40% to 50%.reflectivity, while the laser-recorded data bars might have areflectivity of about 10%.

By this procedure, a lowered reflectivity region is created of about 12microns in width and 25 microns in length. To create the desired 24micron by 25 micron data pixel, the above procedure must be repeatedwith one adjacent track containing two to three similar low reflectivitydata bars. One 24 micron by 25 micron data pixel is thus created by fourto six laser-recorded data bars 2.5 microns wide and 25 microns long,distributed over two adjacent tracks with two to three of the lowreflectivity data bars in each track. This lowered reflectivity 24micron by 25 micron region is designated a data pixel and wouldrepresent a binary “one,” while a similar size, high reflectivity datapixel without any laser recorded data bars would represent a binary“zero.” The objective would be for the contrast ratio between thereflectivity of a “one” data pixel and the reflectivity of a “zero” datapixel to be in the range of about 1.5:1 to 2:1, which would besufficient for data detection with low error rate.

The use of a large data pixel reduces the typical data capacity of fourmegabytes for an optical memory card with a 35 mm storage stripe on it.For example, a 24 micron by 25 micron data pixel would normally containfive data spots per track, and thus the two tracks would normally havecontained ten data spots where now there is only one data pixel. Thusfor the 24 by 25 micron pixel, the data pixel storage capacity of thesame optical memory card would be reduced to about a factor of 10 to 400kilobytes for a 35 mm -wide optical stripe and to about 180 kilobytesfor a 16 mm-wide optical stripe.

The data storage capacity has been reduced. However, for a 16 mm stripe,it is 90 times greater than the two kilobytes stored on plastic cardsusing a PDF-417 patch and 22 times greater than the 8-kilobyte storageof a microchip smart card. The data storage capacity increases to about1600 kilobytes for a 35 mm stripe and about 720 kilobytes for a 16 mmstripe if a data pixel size of 12.5 microns by 12 microns is used.

The method and apparatus for reading the data pixels from a data-pixelcard or data-pixel label will involve either CCD arrays or otherphotodetector arrays. The photodetector array could be of the linearvariety, in which case the card would have to be in motion when read. Inthe case of a two-dimensional photodetector array the card would notrequire motion but instead would be scanned electronically. The use oftwo-dimensional CCD arrays to read data from an optical memory isdescribed in U.S. Pat. Nos. 4,745,484 and 4,864,630. The use of a linearphotodetector array to read optical memory is described in U.S. Pat. No.4,634,850.

A standard one or four-megabyte optical memory card can be used with astandard card reader/writer to create a data-pixel card. The desireddata can be recorded on a card as 2.5 micron data spots. Then a softwareprogram would be loaded into a PC which controls the card reader/writerwhich would read the desired data on the card and in a step-by-stepprocess translate the microscopic spot data into the data pixel format.That data can then be used to record the data on the same card oranother card in the form of large data pixels that can be formed intogroups or a series of 2-D or 1-D bar codes.

The use of the laser-created large data pixels in conjunction with a CCDarray to read the pixels is estimated to reduce the cost of theread-only device by a factor of four from a laser-based, read-onlydevice tracking 2.5 micron data spots. It also permits the read-onlydevice to be portable for use, for example, in readingpersonally-carried medical records in an ambulance, or by militarymedics, or in the event of automobile accidents or other catastrophes.The use of the data pixels permits border crossing visa cards to be readin the field by inspectors, and for digital driver's licenses to bechecked for validity easily. A small, inexpensive, read-only devicewould open the optical memory card market to pay-per-use home T.V. andInternet services and to authorize purchases by welfare recipients inretail establishments.

Also, data-pixel-based two-dimensional bar codes on smart/optical cardscan be used for authentication, validation, authorization, oridentification involving Internet or Intranet E-Commerce transactions asexplained in U.S. Pat. No. 5,932,865, assigned to Drexler TechnologyCorporation. The data-pixel-based information may be in the form of aportable data file database of medical, financial information orsoftware wherein some of which read by the photodetector array istransferred to the microprocessor chip or to a personal computer ornetwork such as the Internet with which said microprocessor chip isinteracting for utilization of said data-pixel-based information. Saiddata-pixel-based information might, for example, include the cardholders demographics, a card serial number, date of card issuance,geographical location of the issuer, types of purchases permitted or notpermitted, date of expiration, maximum dollar value of individualpurchases or purchases over a period of time or any other data relatedto authentication, validation, authorizations and identification thatraises the security of E-Commerce transactions.

Another object of the invention is to devise a method and system to makeCCD-read data-pixel-based two-dimensional bar codes updatable. This isaccomplished by utilizing a laser-recordable optical memory card thatuses a DRAW (direct-read-after-write) laser recording material. A DRAWmaterial records immediately after laser beam exposure and does notrequire a processing operation like photographic film. The opticalmemory card is preferably formatted to facilitate the recording of themicroscopic data spots precisely in the required locations, which willbe grouped into data pixels. By recording of the initial amount of datawhich does not fill the data capacity of the card, at a later time newdata may be added. As indicated previously, a 16 mm optical stripe on acommercially-available optical memory card using 24 by 25 micron datapixels would store 180 kilobytes of data, representing about 90single-spaced typewritten pages. Thus, for example, if the equivalent offive typewritten pages were recorded for each data entry, a total of 18such data entries could be made. If a miniature two kilobyte PDF-417format is utilized the 180 kilobyte data capacity would permit 90 suchminiature PDF-417 patterns to be recorded over a period of time.

Another object is for an optical memory card to be utilized in readingand writing microscopic data spots during some time periods and writingand reading large data pixels during other time periods. This isaccomplished by using a laser-recordable, pre-formatted optical memorycard which uses a DRAW (direct-read-after-write) material. Thepre-formatting of recording tracks and separator bands can beaccomplished by molding, pressing, or by the methods described in U.S.Pat. Nos. 4,542,288 and 4,304,848, assigned to Drexler TechnologyCorporation. The DRAW material is important, since it requires nopost-processing after laser recording and therefore permits hundreds andthousands of data entries over months or years. The track pre-formattingon the optical memory card is desirable since it facilitates preciselocation of the laser-written microscopic data spots so they can laterbe precisely aligned into groups of data spots that create the requiredlarge data pixels. The standard for commercial optical memory cards isto record the microscopic spots on the tracks at the lower end of theoptical memory stripe first. Thus to accommodate writing and readingboth microscopic data spots and the large data pixels, the latter shouldbe recorded on the upper tracks. By this means, a 35 mm optical stripeusing 2.5 micron data spots and 24 by 25 micron data pixels could recordand store, for example, about two megabytes of microscopic data spotsand about 200 kilobytes of data pixels.

When an optical memory card is subject to severe environmentalconditions or misuse such as scratching, high temperature, moisture,chemical or ultraviolet light exposure, particularly over extendedperiods of time, some of the microscopic data spots can be lost. Errordetection and correction (EDAC) systems are usually used to compensatefor such situations. Also, additional microscopic spot data can berecorded redundantly on the card as a backup to the primary data in theevent that critical data is lost. An even more secure approach to theproblem is to record some of the critical data redundantly in the formof large data pixels on the same card. Thus if the primary critical datais lost, the large data pixels can be used for recovery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an optical data card or label of thepresent invention.

FIG. 2 is a side elevation detail of the data card or label of FIG. 1.

FIG. 3 is a diagrammatic plan of a system for reading and writing thedata card or label of FIG. 1.

FIG. 4 is a magnified top plan view of the data card shown in FIG. 1.

FIG. 5 is another magnified top plan view of the data card shown in FIG.1.

FIG. 6 is a photodetector readable version of a magnified 2-D bar codeon data card shown in FIG. 1.

FIG. 7 is a photodetector readable version of a magnifiedone-dimensional bar code on data card shown in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to FIG. 1, an optical memory card 11 is illustratedhaving a size common to most credit cards. The card's substrate material13 is a dielectric, usually a plastic. Polycarbonate is preferred. Thesurface finish of the base should have low specular reflectivity,preferably less than 10%.

Substrate 13 carries strip or patch 17. The strip is typically 35 mm or16 mm wide and extends the length of the card. Alternatively, the stripor patch may have other sizes and orientations. The strip is relativelythin, typically 60-200 microns, although this is not critical. Strips orpatches of laser recording material may be applied to both sides of card11. The stripe or patch may be applied to the card by any convenientmethod which achieves flatness.

The strip or patch 17 is adhered to the card with an adhesive and iscovered by a transparent laminating sheet 76 seen in FIG. 2 which servesto keep strip 17 flat, as well as protecting the strip from dust andscratches. Sheet 76 is a thin, transparent plastic sheet laminatingmaterial or a coating, such as a transparent lacquer. The material ispreferably made of polycarbonate plastic.

The high resolution laser recording material 74 which forms strip 17 maybe any of the reflective recording material which have been developedfor use as direct-read-after-write (DRAW) optical disks, so long as thematerials can be formed on thin substrates. An advantage of reflectivematerials over transmissive materials is that the read/write equipmentis all on one side of the card, the data storage capacity can be doubledby using both sides, and automatic focus is easier. For example, thehigh resolution material described in U.S. Pat. No. 4,230,939 issued tode Bont, et al. teaches a thin metallic recording layer of reflectivemetals such as Bi, Te, Ind, Sn, Cu, Al, Pt, Au, Rh, As, Sb, Ge, Se, Ga.

Materials which are preferred are those having high reflectivity and lowmelting point, particularly Cd, Sn, Tl, Ind, Bi, and amalgams.Suspensions of reflective metal surfaces in organic colloids also formlow melting temperature laser recording media. Silver is one such metal.Typical recording media are described in U.S. Pat. Nos. 4,314,260,4,298,684, 4,278,758, 4,278,756 and 4,269,917, all assigned to theassignee of the present invention.

The laser recording material which is selected should be compatible withthe laser which is used for writing on it. Some materials are moresensitive than others at certain wavelengths. Good sensitivity to nearinfrared light is preferred because near infrared is affected least byscratches and dirt on the transparent laminating sheet. The selectedrecording material should have a favorable signal-to-noise ratio andform high contrast data bits with the read/write system with which it isused.

The material should not lose data when subjected to temperatures ofabout 180° F. (82° C.) for long periods. The material should also becapable of recording at speeds of at least several thousand bits/second.This generally precludes the use of materials that require long heatingtimes or that rely on slow chemical reactions in the presence of heat,which may permit recording of only a few bits/second. A large number ofhighly reflective laser recording materials have been used for opticaldata disk applications.

Data is recorded by forming microscopic data spots in the field of thereflective layer itself, thereby altering the reflectivity in the dataspot. Data is read by detecting the optical reflective contrast betweenthe surrounding reflective field of unrecorded areas and the recordedspots. Spot reflectivity of less than half the reflectivity of thesurrounding field produces a contrast ratio of at least two to one,which is more than sufficient contrast for reading. Reflectivity of thestrip field of about 40% to 50% is preferred with reflectivity of a spotin the reflective field being less than 10%, thus creating a contrastratio of four or five to one. Alternatively, data may also be recordedby increasing the reflectivity of the strip. For example, the recordinglaser can melt a field of dull microscopic spikes on the strip to createflat, shiny spots. This method is described in SPIE, Vol. 329, opticalDisk Technology (1982), p. 202. A spot reflectivity of more than twicethe surrounding spiked field reflectivity produces a contrast ratio ofat least two to one, which is sufficient contrast for reading.

Data strip 17 is intended to provide a data record and has digitalinformation indicia. Digital machine readable data is written inindividual tracks extending in a longitudinal direction, as indicated bythe spot patterns 19 and are usually read in reflection, rather than intransmission. The information density is great because each of the spotsin the spot pattern is approximately 0.6 to 3 microns in diameter with atypical spacing of about 0.6 to 3 microns between spots. The spots arerecorded by a laser in the usual way, for example, as shown in U.S. Pat.No. 4,278,756 to Bouldin et al.

FIG. 1 also represents a laser recordable label, which is technicallyvery similar to an optical memory card, but could be in the form ofindividual labels on in the form of a tape of labels called a labeltape.

With reference to FIG. 2, a card substrate 70 carries an optionalsecondary substrate 72 which is a thin flexible material, only a fewmils thick carrying a laser recording material 74. The secondarysubstrate 72 is adhered to the primary substrate 70 by means of anadhesive or sticky substance. The laser recording material may be any ofthe materials previously discussed. A protective coating 76 is appliedover the laser recording material.

A laser writing apparatus is illustrated in FIG. 3 which illustrates theside view of the lengthwise dimension of the medium of FIG. 1 consistingof a data strip having digital information in combination withmicroscopic data spot information on a card. The data strip portion 41of the medium is usually received in a movable holder 42 which bringsthe strip into the trajectory of a laser beam. A laser light source 43,preferably a pulsed semiconductor laser of near infrared or redwavelength emits a beam 45 which passes through collimating and focusingoptics 47. The beam is sampled by a beam splitter 49 which transmits aportion of the beam through a focusing lens 51 to a photodetector 53.The detector 53 confirms laser writing. The beam is then directed to afirst servo controlled mirror 55 which is mounted for rotation alongaxis 57 in the direction indicated by arrows B. The purpose of themirror 55 is to find the lateral edges of the data strip in a coarsemode of operation and then in a fine mode of operation identify datapaths or sites which exist predetermined distances from the edges.

From mirror 55, the beam is directed toward a mirror 61. This mirror ismounted for rotation at pivot 63. The purpose of mirror 55 is for finecontrol of motion of the beam along the length of the data strip. Coarsecontrol of the lengthwise portion of the data strip relative to the beamis achieved by motion of the movable holder 42. The position of theholder may be established by a linear motor and used by a closed loopposition servo system of the type used in magnetic disk drives.Reference position information in the form of reflective data tracks isprerecorded or pre-formatted on the card so that position error signalsmay be generated and used as feedback in motor control. Upon reading onedata path, the mirror 55 is slightly rotated. The motor moves holder 42lengthwise so that the path can be read again, and so on.

For writing microscopic data spots, mirror 55 is used to identify sitesat predetermined distances from the edges. Mirror 57 moves the scanningbeam lengthwise from site to site. Upon reading one row of sites, mirror55 is slightly rotated. Within a site, mirrors 55 and 57 cooperate tomove the beam in either a zig-zag pattern or a raster-like pattern.Laser data spots are written at designated locations within a datatrack. When one site is written, mirrors 55 and 57 move the beam to thenext site.

As light is scattered and reflected from data spots in the laserrecording material, the percentage of reflected light from the incidentbeam changes relative to surrounding material where no spots exist. Theincident laser beam should deliver sufficient laser energy to thesurface of the recording material to create microscopic data spots inthe data writing mode, but should not cause significant disruption ofthe surface so as to cause difficulty in the lower beam power datareading mode. The wavelength of the laser should be compatible with therecording material to achieve this purpose. In the read mode, power isapproximately 5% to 10% of the recording or writing power.

Differences in reflectivity between a data spot and surrounding materialare detected by well-known methods.

For the most common commercial optical memory cards, the recorded dataspots on the optical memory strip, patch or stripe are approximately 2.5microns in diameter; the highly reflective track is 10 microns wide andis separated by low reflectivity, 2-micron wide bands. The reflectivityof the recording track is in the range of 40% to 50%, and thereflectivity of the separating bands and data spots is about 10%.

FIG. 4 illustrates how the microscopic laser-recorded data spots on anoptical memory strip, patch or stripe are grouped to form large datapixels capable of being read with photodetector arrays such as CCDarrays. The three 10-micron wide reflective tracks 74 are used to recordmicroscopic data spots 71. The 2-micron wide, low reflectivity bands 75separate the 10-micron wide reflective data tracks. The low reflectivitylarge data pixels 72 illustrate how a binary “one” is created by therecording of 15 microscopic spots in a track length sectionapproximately equal to the full track width including separator bands.The group of five data spots in a row is designated a data bar. The highreflectivity large data pixels 73 illustrate how a binary “zero” iscreated. The contrast ratio between data pixels 72 and data pixels 73range between 1.5:1 to 2:1. Since the data spots are about 2.5 micronsin diameter and there are five in a row, the data pixel dimension is12.5 microns by 12 microns in size.

FIG. 5 is similar to FIG. 4, but the larger data pixel dimensions are 25microns by 24 microns, exactly twice as big linearly but four times thearea of the FIG. 4 data pixels. Note that these data pixels are spreadover two tracks of an optical memory strip, patch or stripe whereasthose in FIG. 4 occupy one track. Data pixel 82 represents a binary“one,” and data pixel 83 represents a binary “zero.”

FIG. 6 illustrates an optical memory card 91 containing binary “ones”and “zeros” in a pattern that can-be called a quad-density data format95 as described in U.S. Pat. Nos. 4,634,850 and 4,786,792 assigned toDrexler Technology Corporation or it can take the form of a 2-D bar codeor a group or series of miniature PDF-417 bar codes. These two patentsexplain how such data pixels are read by a linear photodetector arraysuch as a CCD array. An area photodetector array such as a CCD areaarray also can be used as described in U.S. Pat. Nos. 4,745,484 and4,864,630, both assigned to Drexler Technology Corporation. If the datapixels are large enough a laser can scan the data pixels by rasterscanning and the reflected laser light can be detected by one or morephotodetectors.

Substrate 93 carries optical memory strip, patch or stripe 97. Thepreferred dimensions of the data pixels of the present invention fallwithin the upper range of the preferred linear dimensions of the '850and '792 patents, namely, 10 microns to 35 microns. The method ofreading such quad-density patterns with linear CCD arrays is explainedin detail in those two patents. A key point is that to minimize errorsat least two photosensitive detectors in the photodetector or CCD arrayshould view each data pixel. Thus to be practical, at least three suchphotodetectors would be preferred. To read the data pixels with linearphotodetectors or CCD arrays, there must be linear motion of the cardand its quad-density pattern across the photodetectors as explained inthe two referenced quad-density-related '850 and '792 patents. Also,under selected system design conditions, two-dimensional photodetectorarrays such as CCD arrays can be used to read encoded stationary opticalmemory cards by the techniques described in U.S. Pat. Nos. 4,745,484 and4,864,630. Also, note that the quad-density or miniature 2-D bar codeformat patterns of the present invention result in much higher datastorage capacities than the PDF-417 format since they use data pixelsizes about one order of magnitude smaller than the PDF-417two-dimensional bar code patterns whose smallest pixel size appears tobe about 150 microns.

FIG. 7 is similar to FIG. 6 except that the data pixels were assembledas a one-dimensional bar code 105 rather than a 2-D bar code. If the onedimensional bar code is large enough it can be read with a laser beamscanner and one or more single photodetector(s). An optical memory cardor label 101 carries a laser recordable optical memory stripe or patch107 mounted on a plastic card base 103. The directions of the wide andnarrow lines comprising the one-dimensional bar codes can be eitherparallel to or perpendicular to the pre-formattedtracks in thelaser-recordable media. These wide and narrow 1-D bar code lines areformed from data pixels which in turn are formed from groups oflaser-recorded spots on an optical storage medium as illustrated inFIGS. 4 and 5.

Consider the example where the wide and narrow lines of aone-dimensional bar code are parallel to the pre-formatted tracks in thelaser-recordable media. Some of these lines are wide, representing onedata state, while other lines are narrow representing another datastate. The narrow lines are written by a series of adjacent spots alongthe length of the track in order to provide optical contrast. Sometracks are filled in the widthwise direction, forming a wide line, andsome tracks only partly filled in the widthwise direction, forming anarrow line. Where narrow and wide lines can be formed in each trackforming two data states, then empty tracks can represent a third datastate. Note that in this example with a one-dimensional bar code insteadof relying upon optical contrast for ones and zeros, now the ones andzeros are represented by thick and thin lines. The absence of a line ina track is yet a third information state which can be present so thattracks can contain a wide line, a narrow line or no line. This thirdinformation state can be used as a marker for control information,distinguishing such digits from user data. Note that when the word“track” is used in this paragraph, when applicable, it can refer togroups of tracks.

What is claimed is:
 1. A method of creating digital data pixels in theform of miniature bar code(s) readable with CCD arrays fromlaser-written, microscopic data spots comprising, generating an opticalbeam capable of recording microscopic data spots on an optical datastorage medium, the spots having a characteristic width, providing aDRAW (direct-read-after-write) optical data storage medium capable ofbeing laser-recorded with said microscopic data spots, pre-formattingsaid medium with tracks for recording said data spots where the trackhas a characteristic width sufficient to accommodate two to six of saiddata spots if they were arranged in close proximity to one another in acolumn across said track width, optically recording a row of said dataspots along and within a first track in a manner so as to form a firstlaser-recorded data bar which has the approximate width of said dataspots and a length of approximately one to two times the track width,laser recording one to five more data bars parallel and adjacent to saidfirst data bar within the width of the same track and having a lengthsimilar to that of the first data bar, identifying one data pixel amongmany data pixels as a region whose smallest dimension is at least sevenmicrons on said optical storage medium and which encompasses two to sixof said data bars and that portion of said track that contains said databars, and grouping data pixels to form bar codes or bar code data bases.2. The method of claim 1 where said optical data storage medium isdisposed on one of optical memory cards, label tape or individuallabels.
 3. The method of claim 1 where said bar codes are 2-D bar codesof a type including the following: PDF-417, Aztec, Code 16K or Code 49.4. The method of claim 1 where said bar codes are of the 1-D bar codetype including the following: Code 39, Code 93, Code 128, Code 11, CodeB, Coda Bar, EAN, UPC, MSI, PostNet, Royal Mail (RM 45CC) or Telepan. 5.The method of claim 1 further defined by writing adjacent spots in thewidthwise direction as well as the lengthwise direction until most ofthe entire width of the track is written upon.
 6. The method of claim 1further defined by writing, in some tracks, spots in the lengthwisedirection in the center of the track, leaving space in the track on bothsides of the spots, and in other tracks spots in the widthwise directionas well as the lengthwise direction until most of the entire width ofthe track is written upon.
 7. The method of claim 1 further defined bywriting data across the width of the optical recording medium with alaser while moving the recording medium in the lengthwise direction andagain writing data across the width of the medium.
 8. A method ofcreating digital data pixels in the form of miniature bar codes readablewith CCD arrays from laser-written, microscopic data spots comprising,providing a laser capable of recording microscopic data spots on a DRAW(direct-read-after-write) optical data storage medium, pre-formattingsaid medium with tracks for recording said data spots where the track iswide enough to accommodate two to six said data spots if they werearranged in close proximity to one another in a column across said trackwidth, laser recording a row of said data spots along and within a firsttrack such that said spots form a first laser-recorded data bar whichhas the approximate width of said data spots and a length ofapproximately two to four times the track width, laser recording one tofive more data bars parallel and adjacent to said first data bar withinthe width of the same first track and having a length similar to that ofthe first data bar, laser recording in a second track adjacent to thefirst track two to six data bars of similar widths and lengths to thosein the first track, identifying one data pixel among many data pixels asa region whose smallest dimension is at least seven microns on saidoptical storage medium and which encompasses four to twelve of said databars in the first and second tracks and that portion of the two trackscontaining said data bars, and grouping data pixels to form bar codes orbar code data bases.
 9. The method of claim 8 where said optical datastorage medium is disposed on one of optical memory cards, label tape orindividual labels.
 10. The method of claim 8 where said bar codes are2-D bar codes of a type including the following: PDF-417, Aztec, Code16K or Code
 49. 11. The method of claim 8 where said bar codes are ofthe 1-D bar code type including the following: Code 39, Code 93, Code128, Code 11, Code B, Coda Bar, EAN, UPC, MSI, PostNet, Royal Mail (RM45CC) or Telepan.
 12. A method of creating digital data pixels in theform of miniature bar codes readable with CCD arrays from laser-written,microscopic data spots comprising, providing a laser capable ofrecording microscopic data spots on a DRAW (direct-read-after-write)optical data storage medium, pre-formatting said medium with tracks forrecording said data spots where the track is wide enough to accommodatetwo to six said data spots if they were arranged in close proximity toone another in a column across said track width, laser recording a rowof said data spots along and within a first track such that said spotsform a first laser-recorded data bar which has the approximate width ofsaid data spots and a length of approximately three to six times thetrack width, laser recording one to five more data bars parallel andadjacent to said first data bar within the width of the same first trackand having a length similar to that of the first data bar, laserrecording two to six data bars of similar widths and lengths in a secondtrack adjacent to the first track and two to six data bars in a thirdtrack which is adjacent to either the first or second track, identifyingone data pixel among many data pixels as a region whose smallestdimension is at least seven microns on said optical storage medium andwhich encompasses six to eighteen of said data bars in the three tracksand that portion of the three tracks containing said data bars, andgrouping data pixels to form bar codes or bar code data bases.
 13. Themethod of claim 12 where said optical data storage medium is disposed onone of optical memory cards, label tape or individual labels.
 14. Themethod of claim 12 where said bar codes are 2-D bar codes of a typeincluding the following: PDF-417, Aztec, Code 16K or Code
 49. 15. Themethod of claim 12 where said bar codes are of the 1-D bar code typeincluding the following: Code 39, Code 93, Code 128, Code 11, Code B,Coda Bar, EAN, UPC, MSI, PostNet, Royal Mail (RM 45CC) or Telepan.
 16. Amethod of creating digital data pixels in the form of miniature barcodes readable with CCD arrays from laser-written, microscopic dataspots comprising, providing a laser capable of recording microscopicdata spots on a DRAW (direct-read-after-write) optical data storagemedium, pre-formatting said medium-with tracks for recording said dataspots where the track is wide enough to accommodate two to six said dataspots if they were arranged in close proximity to one another in acolumn across said track width, laser recording a row of said data spotsalong and within a first track such that said spots form a firstlaser-recorded data bar which has the approximate width of said dataspots and a length of approximately four to eight times the track width,laser recording one to five more data bars parallel and adjacent to saidfirst data bar within the width of the same first track and having alength similar to that of the first data bar, laser recording two to sixdata bars of similar widths and lengths in each of a second track, thirdtrack, and fourth track, which form a group of four adjacent tracks,identifying one data pixel among many data pixels as a region whosesmallest dimension is at least seven microns on said optical storagemedium and which encompasses eight to twenty-four of said data bars inthe four tracks and that portion of the four tracks containing said databars, and grouping data pixels to form bar codes or bar code data bases.17. The method of claim 16 where said optical data storage medium isdisposed on one of optical memory cards, label tape or individuallabels.
 18. The method of claim 16 where said bar codes are 2-D barcodes of a type including the following: PDF-417, Aztec, Code 16K orCode
 49. 19. The method of claim 16 where said bar codes are of the 1-Dbar code type including the following: Code 39, Code 93, Code 128, Code11, Code B, Coda Bar, EAN, UPC, MSI, PostNet, Royal Mail (RM 45CC) orTelepan.
 20. A method of creating digital data pixels in the form ofminiature bar codes readable with CCD arrays from laser-written,microscopic data spots comprising, providing a laser capable ofrecording microscopic data spots on a DRAW (direct-read-after-write)optical data storage medium, pre-formatting said medium with tracks forrecording said data spots where the track is wide enough to accommodatetwo to six said data spots if they were arranged in close proximity toone another in a column across said track width, laser recording a rowof said data spots along and within a first track such that said spotsare either in close proximity, contiguous, or overlapping one another soas to form a first laser-recorded data bar which has the width of saiddata spots and a length of approximately five to ten times the trackwidth, laser recording of at least one more data bar adjacent to saidfirst data bar within the approximate width of the same track and havinga length similar to that of the first data bar, laser recording two tosix data bars of similar widths and lengths in each of a second track,third track, fourth track, and fifth track, which form a group of fiveadjacent tracks, identifying one data pixel among many data pixels as aregion whose smallest dimension is at least seven microns on saidoptical storage medium and which encompasses ten to thirty of said databars in five tracks and that portion of the five tracks containing saiddata bars, and grouping data pixels to form bar codes or bar code databases.
 21. The method of claim 20 where said optical data storage mediumis disposed on one of optical memory cards, label tape or individuallabels.
 22. The method of claim 20 where said bar codes are 2-D barcodes of a type including the following: PDF-417, Aztec, Code 16K orCode
 49. 23. The method of claim 20 where said bar codes are of the 1-Dbar code type including the following: Code 39, Code 93, Code 128, Code11, Code B, Coda Bar, EAN, UPC, MSI, PostNet, Royal Mail (RM 45CC) orTelepan.
 24. An updatable optical memory card containing miniature barcodes readable with a photodetector array comprising a wallet-size cardhaving a strip, patch or stripe of optical contrast pre-formatted DRAWlaser recording material disposed thereon, a plurality of laser-writtenmicroscopic data spots create a plurality of data bars recorded on saidstrip with at least two said data bars on each track having a trackwidth at least three times greater than the width of the data bars andthe combination of at least two adjacent tracks having said data barsrecorded thereon, forming a data pixel among many data pixels as aregion whose smallest dimension is at least seven microns and whichencompasses at least 2n data bars which are approximately n to 2n trackwidths long and that portion of the n tracks encompassed containing atleast 2n said data bars, and where said data pixels in the form ofminiature bar codes are capable of being read with a photodetectorarray.
 25. The updatable optical memory card of claim 24 wherein saidphotodetector array is a CCD array.
 26. The updatable optical memorycard of claim 24 where the number of tracks n can range from one to ten.27. The updatable optical memory card of claim 24 where the data pixellinear size dimension ranges from approximately one track width to tentimes the track width.
 28. The updatable optical memory card of claim 24where said miniature bar codes are in the form of miniature 2-D barcodes.
 29. The updatable optical memory card of claim 24 where some ofthe data recorded in microscopic data spots on said card is alsorecorded redundantly on the same card using data pixels which are atleast twice as large as said microscopic data spots.
 30. An opticalmemory label tape or individual labels for attaching to documents,plastic cards and manufactured products containing miniature bar codescomprising a strip, patch or stripe of optical contrast pre-formattedDRAW laser recording material in the form of single or multiple labelsin the form of a tape, a plurality of laser-written microscopic dataspots create a plurality of data bars recorded on said strip, patch orstripe with at least two said data bars on each track having a trackwidth at least three times greater than the width of the data bars andthe combination of at least two adjacent tracks having said data barsrecorded thereon, forming a data pixel among many data pixels as aregion whose smallest dimension is at least seven microns, thatencompasses at least 2n data bars which are approximately n to 2n trackwidths long and that portion of the n tracks encompassed containing atleast 2n said data bars, and where said data pixels in the form ofminiature bar codes are capable of being read with a photodetectorarray.
 31. The optical memory label tape or individual labels of claim30 wherein said photodetector array is a CCD array.
 32. The opticalmemory individual labels of claim 30 which are utilized for a purposeand said purpose is authentication, validation, authorization, oridentification of said documents, plastic cards and manufacturedproducts.
 33. The optical memory label of claim 30 where the number oftracks n can range from one to ten.
 34. The optical memory label ofclaim 30 where the data pixel linear size dimension ranges fromapproximately one track width to ten times the track width.
 35. Theoptical memory label tape of claim 30 which is utilized for a purposeand said purpose is authentication, validation, authorization, oridentification of said documents, plastic cards and manufacturedproducts.
 36. The optical memory label tape or individual labels ofclaim 30 where the labels that comprise the tape or the individuallabels have serial numbers or other features that distinguish one labelfrom another label.
 37. A method of recording digital data in the formof miniature bar codes comprising: pre-formatting a length of directread after write (DRAW) optical data recording medium with opticallyreflective parallel linear regions having a narrower linear edge regionwidth than the edge-to-edge spacing, thereby defining data tracks ofcharacteristic width, in a track, writing a number of adjacent spots inthe lengthwise direction, each spot having a dimension less than saidtrack width, the spots extending for a predetermined distance along thelength of the track, thereby changing the optical contrast of the trackfor said distance, the number of adjacent spots forming a oblong barencoding a first data state, providing unwritten space for saidpredetermined length along the track, encoding a second data state, andcombining written and unwritten spaces in a plurality of tracks to forma two-dimensional miniature bar code.